Antibacterial Activity of Solanum torvum Leaf Extract and Its Synergistic Effect with Oxacillin against Methicillin-Resistant Staphyloccoci Isolated from Dogs

Abstract

Methicillin-resistant staphylococci (MRS) have been considered a veterinary and public health threat that needs to be addressed, as they are known to cause serious infections, with limited therapeutic options. Thus, in this study, we aimed to examine the potential antibacterial activity of the leaf extract of Solanum torvum against MRS isolated from clinically healthy dogs. In total, seven mecA-positive Staphylococcus isolates tested in this study were identified using 16S rRNA gene sequencing, and all of them were classified as multidrug-resistant using disk diffusion tests. According to gas chromatography-mass spectrometry analysis, the main phytochemical components found in the leaf extract were hexadecanoic acid and its ethyl ester and 9,12,15-octadecatrienoic acid, ethyl ester, (Z,Z,Z). The minimum inhibitory concentration (MIC) breakpoints for the leaf extract against all tested isolates ranged from 2 to 16 mg/mL, while the MIC breakpoints for oxacillin were from 2 to 512 mg/L. Although varying effects were found, the positive effects of the leaf extract were most evident in combination with oxacillin. These results suggested that S. torvum leaf extract may complement classical antibiotics and may potentially drive the development of an effective therapeutic option for MRS.

Synergistic antibacterial action of the iron complex and ampicillin against Staphylococcus aureus

“…Antimicrobial activity and synergistic effect of Fe16, AMP and Fe16 + AMP was tested by the checkerboard assay [ 39 ]. Briefly, Fe16 was placed in 96-well microplates diluted twofold in Mueller Hinton broth (Sigma Aldrich, USA) along the vertical rows and AMP was cross-diluted horizontally by twofold serial dilution.…”

<em>Cannabis sativa</em> CBD Extract Exhibits Synergy with Broad-Spectrum Antibiotics against <em>Salmonella typhimurium</em>

“…(3) FICI= FIC AB + FIC CBD The FICI was evaluated as follows: synergy (FICI < 0.5), partial synergy (0.5 ≤ FICI ≥ 0.75), additive (0.76≤ FICI ≥ 1), indifference (1 ≤ FICI ≥ 4), or antagonism (FICI > 4). The average MIC from three independent experiments were used for these equations [37].…”

“…The lack of antibiotic development in the 21 st century has enhanced the need for researchers to repurpose antibiotics and determine treatment methods that help retain their antibacterial function. The use of agents extracted from botanical sources as synergetic additives has been an area of growing interest over recent history [15,37,39,40]. This study explored the potential synergistic activity between C. sativa L. CBD extract and three broad spectrum antibiotics: ampicillin, kanamycin, and polymyxin-B.…”

In Vitro Synergistic Inhibitory Effects of Plant Extract Combinations on Bacterial Growth of Methicillin-Resistant Staphylococcus aureus

“…The ability of MRSA to tolerate conventional antibiotics leads to difficult-to-treat infections and limits the therapeutic options available [4,7]. Methicillin resistance in Staphylococci is mediated by the mecA gene, which encodes a modified penicillin-binding protein 2a (PBP 2a) that results in resistance Pharmaceuticals 2023, 16, 1491 2 of 15 to beta-lactam antibiotics by causing a low binding affinity [8,9]. Furthermore, over time, MRSA has developed resistance to other antibiotic classes, including fluoroquinolone, macrolide, aminoglycoside, and clindamycin [10].…”